1. Field of the Invention
This invention relates to a phase shift mask, in particular to a structure of an attenuation type phase shift mask which attenuates light of exposure wavelength and a process for the same.
2. Description of the Background Art
The making of semiconductor integrated circuits of large scale and the miniaturization thereof has been remarkable. Together with that the miniaturization of circuit patterns formed on semiconductor substrates (hereinafter referred to simply as wafers) has been progressing rapidly.
Particularly, photolithographic technology is widely recognized as a basic technology in pattern formation. Accordingly, a variety of developments and improvements have been carried out up to the present time. The miniaturization of patterns has been an unending process and the requirements for the improved resolution of patterns have become more demanding.
Accordingly, in recent years, a phase shift exposure method using a phase shift mask has been proposed as a technology to satisfy these requirements and “Phase Shift Mask and Process for the Same as well as Exposure Method Using That Phase Shift Mask” (hereinafter referred to as background technology 1), disclosed in the Japanese Patent Laying-Open No. 5-285327(1993), “Process for Phase Shift Photo Mask Blanks, Phase Shift Photo Mask Blanks and Phase Shift Photo Mask” (hereinafter referred to as background technology 2), disclosed in the Japanese Patent Laying-Open No. 8-74031(1996), and “Titanium Nitride Thin Film Formation Method” (hereinafter referred to as background technology 3), disclosed in the Japanese Patent Laying-Open No. 8-127870(1996), are sited as a technology related to the above phase shift mask.
Background technologies 1 and 2 concretely disclose a molybdenum silicide type halftone phase shift mask and a process for the same, wherein a reactive sputtering using a direct current magnetron discharge is adopted in a film formation style of phase shifter film.
In addition, in background technology 1, as for supplied gases, Ar is used for an inert gas, O2 or (O2+N2) is used for a reactive gas while a mixture gas system is adopted as a gas supply system.
In addition, in background technology 2, as for supplied gases, Ar is used for an inert gas, NO is used for a reactive gas while a mixture gas system is adopted as a gas supply system in the same way as in background technology 1.
In addition, in background technology 3, a reactive low pressure sputtering method through a direct current magnetron discharge and a unit therefore are concretely disclosed and the purpose of this background technology 3 is to provide a titanium nitride thin film formation method of which the filling in characteristics inside of microscopic holes is maintained at an excellent level and of which the film thickness distribution of the thin film on the substrate surface is uniform.
In order to achieve this purpose, in background technology 3, a so-called long throw sputtering method (hereinafter referred to as LTS method) is adopted where the pressure is maintained at 1×10−1 Pa (7.5×10−4 Torr) or less under an Ar+N2 gas atmosphere and the mixture gas composition is set at 1/8≦Ar/N2≦1/3 as a flow amount ratio in order to gain a uniform titanium nitride thin film distribution. Here, as for the distance (T/S) between the target and the substrate, 140 mm, 170 mm and 200 mm are selected.
Based on the technologies shown in the above described background technologies 1 to 3, however, in the case that a thin film which is used as a phase shift mask, particularly a phase shifter film, is formed a thin film which has sufficient optical characteristics (particularly transmittance) cannot be formed.
In particular, a molybdenum silicide type phase shifter film which is formed based on background technologies 1 and 2 cannot be provided for practical use because the transmittance of the halftone phase shift mask in the ArF laser exposure wavelength (193 nm) is very small.
In addition, film formation is possible only when the transmittance of a halftone phase shift mask in the KrF laser exposure wavelength (248 nm) is less than 8% which becomes a problem in practical use.
Accordingly, this invention is provided to solve the above described problems and provides a halftone type phase shift mask which can be applied in an ArF laser or a KrF laser by using a molybdenum silicide type material. In addition, relating to this phase shift mask, the provision of a process for the gaining of that phase shift mask in addition to the provision of a phase shifter film and a process for the same, blanks for a phase shift mask and a process for the same, an exposure method by using that phase shift mask, a semiconductor device manufactured by using that phase shift mask, a defect inspection method of that phase shift mask and a defect correction method of that phase shift mask are additional purposes.
Based on this invention, as shown in the above described purposes, a halftone phase shift mask which can be applied in an ArF laser or in a KrF laser can be formed of a molybdenum silicide type material. Since the same production process and production units as are used in background technologies 1 or 2 can be applied as they are for the molybdenum silicide type material a new large scale investment for facilities can be avoided. It also becomes possible to save the labor, time and development costs which would be needed for developing a new production process.
More concretely, it becomes possible to form a molybdenum silicide type thin film through an LTS method, that is to say, a reactive sputtering method by means of direct current magnetron discharge so as to form a thin film which has an excellent transmittance by applying the above film to a phase shifter film and, thereby, it becomes possible to manufacture a halftone type phase shift mask for ArF laser exposure which used to be impossible through a sputtering system as shown in the background technology.